This thesis analyses the simplification of fashion in the French "beau monde" at the end of the eighteenth century. It reveals that the simplified fashion of the 1770s and 1780s was the result of a new feeling for nature. New perceptions of the body led physicians to plead for a new fashion, more respectful of the natural characters of the body. On the aesthetic level, natural simplicity was meant to be the only way to recover original truth and energy. Moreover, anglomania, by way of sustained exchanges with England, contributed to the development of a simpler and more egalitarian fashion. This new feeling for nature reflects profound changes in the French society at the end of the century. The idea of nature, defined according to the values and ideals of a rising bourgeoisie, conveyed a bourgeois spirit no longer restricted to a narrow social group.